1. Field of the Invention
The present invention relates to photolithographic projection and in particular to a simulator of an optical intensity distribution, a computer implemented method for simulating the optical intensity distribution, a method for correcting a mask pattern, and a computer program product for the simulator.
2. Description of the Related Art
When a semiconductor device is manufactured by using lithography process, a light component incident on a surface of a substrate is blocked by a protrusion on the substrate. In this case, calculating an optical intensity distribution around the protrusion by using Maxwell equation requires a great investment of time. Therefore, such calculation lacks in practically. In an earlier method, it is assumed that the all components of the light enter the surface perpendicularly and the all components are reflected from the surface perpendicularly to simplify the calculation. However, the result of the earlier method deviates from an actual result of the optical intensity distribution. Japanese Patent Laid-Open Publication No. Hei 9-43828 describes a method for incorporating an effect of the protrusion on a rate of dissolution into a development simulation easily. However, in a simulation for simulating the optical intensity distribution, a method for simulating the optical intensity distribution precisely at high speed when the protrusion is disposed on the substrate has not been proposed.